Descent into Darkness
by Minirose96
Summary: It was only meant to be a game, to prove a man's insanity, but Sherlock's gotten himself in way over his head. Possessed by a demon literally hell-bent on breaking his mind and spirit, he had do nothing but watch as the creature destroys his carefully crafted life. (Demonlock!) (Non-Con!) (Graphic depictions of violence!) (You've been warned!)
1. An Experiment

****Disclaimer: I own nothing! I claim nothing! I'm just borrowing the characters for my own pleasure and the pleasure of whoever reads this!****

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**Chapter One**

**An Experiment**

The case left Sherlock more curious than usual. A man, a satanic worshiper, had killed thirteen people in less than a week, and then had turned himself in, claiming a demon he summoned had taken control of his body and done those things. Preposterous.

And yet, Sherlock was curious, because upon examining the man's flat, the most peculiar of symbols and items were drawn and laid out on the floor of the man's living room.

The symbol was an intricate star enclosed in a circle. It was painted onto the ground with blood. Testing later on would show that it was pig's blood, not human blood.

Inside the circle, five black candles were melted down to their bottoms, and each was also aligned with a different point on the star. There was a bowl in the center, with bones and more congealed blood. The full skeleton of a large snake sat at the top of the symbol, and chicken feathers were scattered throughout the entire design.

He was dubious at best that such a design, not matter how disturbing to the average mind, could summon any sort of creature, aside from flies, but the design had a profound affect on several of the others in the room. Lestrade cursed under his breath, and Donovan created the sign of the cross on her chest. Even John, not a religious man since the war, muttered a small prayer under his breath. A few individuals asked to leave the room, their faces pale.

He cataloged their reactions and stored the information away as he knelt down to examine it more closely. No one else would get as close. He spotted a journal , half concealed under a chair, and pulled it from it's hiding place. It was still open on the page that it's owner had last read from.

It was in an ancient Latin text, one that predated current translations. How the murderer had been able to read it was beyond him. He could though, and he did.

Sherlock began to read.

It was instructions on how to summon a demon, including how to make the circle in front of him and a chant in an ancient tongue that would draw a demon to the circle. It was ridiculous, but it also made him curious, so he filed the information away, and took pictures in his mind of the circle, a new experiment already being planned.

The book was quickly handed over as evidence. He didn't need it anymore anyway.

Aside from the circle and the book, there was no evidence of so-called 'demonic activity.'

The man was charged, sentenced, and sent to a mental institution, still screaming of demons and the devil inside everyone. Overall, it was a simple, open and shut case.

But Sherlock was curious. He was also bored. When curiosity and boredom intersected in his mind, he experimented.

He wanted to recreated the circle in his own home, just to see what could have convinced the man that demons were anything but myth and superstition.

So, he purchased and gathered the supplies.

The feathers came from a small farm just outside of London whose owners owed him a favor.

The five black candles came from a specialty store.

The snake skeleton, he purchased from a voodoo shop owned by an old woman who clearly didn't believe in the ideas of the products she sold.

The blood - human instead of pig's because the text book had said that human blood was more potent - he obtained from Molly. She had, of course, asked why he needed it, but he had merely told her it was for an experiment.

It wasn't technically a lie.

Now, he painted the symbol from the house onto the floor of his flat with the blood Molly had given him. He had learned, after a bit of research online, that the symbol was a pentagram, an inverted pentacle and a symbol used by Satan worshipers for centuries to communicate with the devil or to summon creatures from hell itself.

As if some sort of entity actually existed.

He set the candles in position and lit them. The small flame on each seemed to dance for a moment before evening out as the last one was lit. He blamed it on a slight breeze.

Next, he set the bowl of bones - he chose chicken, to go with the feathers - and more blood in the center.

The snake skeleton at the top of the pentagram and the feathers scattered throughout the entire symbol completed it.

He stood and examined his work.

It was an almost exact replica of the symbol from the scene.

He smirked. Time to disprove an entire religion, he thought, rolling up his sleeves to keep them from getting dirty when he cleaned the mess up in a few minutes.

From memory, he began to chant the Latin incantation as printed from the text. Roughly, it translated into this:

_I, son of mortal ties and made of mortal flesh and blood_

_Call from the depths a follower of the first fallen one._

_Through blood and bone I summon the from hell and call you into this world__  
_

_And Offer you haven within mortal flesh and blood._

To end the ritual, he cut his palm with a small blade made of silver and allowed a few drops to fall into the bowl at the center of the circle.

Sherlock watched and waited for several minutes, but not even a feather shifted.

He smirked. As he expected, nothing. Just the false notions of a foolish man trying to reconcile his mind with what he'd done to thirteen people.

He turned his back on the circle and grabbed a pail of water to begin washing away the circle before Mrs. Hudson got home and yelled at him for damaging the floor.

He shifted, ready to slosh and spread the water across the circle, but he froze mid motion as he saw the being now standing in its center. The water splashed. Some of it went onto the floor, but the majority remained inside the bucket.

The creature looked almost like a dense reptilian fog. It's skin was like smoke, but it was so defined that he could see each individual scale as they shifted in and out. It stood on it's hind legs, with clawed hands and feet. It all shifted in and out of focus though, like a cloud changing shape. Except for the eyes. The eyes were unchanging, two centers of pitch black darkness that only resided in nightmares.

Sherlock dropped the bucket, which remarkably didn't spill, and took a step back.

He never admitted to fear. He kept himself above fear, and other emotions. But now, he was afraid, terrified, even, especially as the creature stepped out of the circle and followed him, taking slow, even steps, as though it had all the time in the world to catch him.

Sherlock didn't know what to do. That wasn't meant to work. It was just pretend. Demons weren't real.

"Guess again, son of mortal flesh." Its voice was rough and gravelly, like listening to rocks tumbling down a sheet of metal.

He backed into a wall, pinned. Suddenly, he couldn't move.

The creature got closer, stopping less than a foot from him.

It raised on of its clawed hands and caressed his cheek. It was cold, like being brushed by dry ice.

"Thank you for providing such a healthy vessel." It was almost mocking.

Then it's claws - or whatever you wanted to call them - began to sink into his head. They didn't pierce the flesh, but still he felt as though he were being filled and invaded, cut and gouged painfully.

He screamed in agony, and the demon swooped in, seeming to dive into his open mouth. He felt like he was choking.

It was like burning from the inside out.

And then, everything went black.

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Whoo! Another story for me to obsess over! I had a mighty craving for some dark, dirty, evil Sherlolly Demonlock. The only one that seems to be around is Cosmic by Adi_Who_is_also_Mou (Whic his a great little smut filled present) so I decided to write one myself to satisfy my cravings XD Kinda like craving chocolate and baking brownies to get the chocolate.

So, enjoy my chocolate. Or not. Because this really will be an evil story.

Hehehe.

Until Next Time! :*


	2. Trapped

****Disclaimer: I own nothing! I claim nothing! I'm just borrowing the characters for my own pleasure and the pleasure of whoever reads this!****

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**Chapter Two**

**Trapped**

Sherlock blinked. Once. Twice. His eyes shifted from pitch black to a dark blue green and back again between the blinks. He smirked. No, the thing, the creature inside him, smirked, an ugly, distorted form of the look Sherlock wore so well.

He examined himself, the new flesh and bone that concealed him. Strong, fit, intelligent. Not too intelligent, obviously.

Joints popped one by one as he settled into the skin. He rolled his shoulders and wrists, cracked the bones in his neck.

A near perfect specimen, one that pleased him greatly.

He'd already read the man's greatest fears, buried in the back of his mind. Surprisingly, he had no problem with murder. He didn't care about what happened to him, or who he killed or what he saw. His biggest fear, was that he would be left alone. That he would push away everyone who cared about him until there was no one left. Not even...

_What's this?_

Sherlock's face distorted into a manic grin. "So, the little human has tried to hide things." His voice was a mixture of gravel and the body's own. That would adjust as he settled into the skin.

He pulled up memories, names, almost like reading a book on how to destroy a person's - this person's - life.

The most important people, so easy.

John Watson. Retired army doctor. Once had a psychosomatic limp. Currently married to, _ooh, _an ex assassin who still had her claws. A little girl popped into his mind as well. Their daughter. Amelie. So young, sweet and innocent. This fool loved his god daughter so much.

_Let's see if I can't give the man something to truly limp for._ The wife and daughter would follow suit once his attack on John had been made.

Martha Hudson. Landlady with a _very _interesting past. The husband, he remembered. Currently burning exquisitely in hell. Abusive past. A few cruel words and actions, and she would break. Oh how he loved when the elderly suffered. Weak, pathetic old woman.

Gregory Lestrade.

Oh, A Detective Inspector for the NSY. A rough man, hard life. So much doubt in this man. this body fears in Lestrade finding out his crimes. A friend. A source of entertainment. Cases.

Best destroy that. Can't leave him with anything even remotely fun, after all.

So few people. It would be even more gratifying when he left his man a hated husk after destroying everything.

Wait.

A blink, and the dark blue eyes faded, revealing the true black.

Unusual. The mind was trying to hide something away from him.

When a body was possessed, the mind fell open like a book. This felt different, as though the pages had been glued together, hiding some of the contents.

It made him curious.

The seam where the seal had been made was messy. Done hastily. Even more intriguing.

He heard a blood curling scream echoing through the mind as he tore apart the bindings.

A slew of information came flooding forth. Most importantly, a name.

Molly Hooper. Pathologist at Bart's. Last encounter involved getting slapped. No further contact. Some interesting feelings and thoughts for this one. Not just a friend, but he tries so desperately hard to ignore. Several feelings _are _ignored. He had hoped that they would go away.

The one who matters most.

_Poor, poor mortal. I'm going to destroy her and make you feel every second of her pain. _

Sherlock - the creature controlling him - smirked as he heard another scream, desperate, beautiful.

_"Leave her alone!"_

As if he would listen.

The first thing then, was to destroy her. Everything else would fall into place.

_Kind, sweet little Molly. I can't wait to see you bleed and scream and struggle until you've given up on everything. It will be so beautiful._

_... ... ... ... ... ... ... _

His mind Palace was in shambles when Sherlock finally awoke. He was trapped in his mind, in the house he had created. Any and all attempts to leave failed. But he could somehow feel his limbs moving without his permission, shifting and stirring.

His head pounded. Then he looked up, and saw a black smoke traveling along the ceiling. Forcing each of the doors open. His blood ran cold.

He tried to seal off certain sections. His friends, his family, nothing held. He couldn't control anything.

Even the door he'd kept sealed for months, since his last encounter with Molly, burst open, revealing so much before him. The apparitions he made to represent everyone in his life wandered, distorted and ugly in comparison to the light he tried to capture in each of them.

The one representing John scowled, his features set in hard lines. He glared whenever Sherlock asked for advice from him, much like he would from the true John Watson. Where his John would answer, help, this one just sneered, and turned from him.

The Lestrade of his palace looked disgusted, disappointed, almost murderous. He dared not go near him, and Lestrade guarded the corridors that contained his previous case files, as if barring him from any more investigations.

His mother and father were terrified of him. They hid themselves from his view, though he searched. He wasn't certain that they even remained within the walls of his palace anymore.

His brother just gave him a blank look, when he passed by the room that represented his office.

Redbeard cowered and snapped when he attempted to go to him for comfort. He left the dog alone and continued, a childhood ache of loss reopened.

Moriarty strolled close behind him, no longer chained in the deepest, darkest corners of his mind. He threw taunts and jibs at Sherlock as they walked. Redbeard let him pet him.

He was worried, when he couldn't find Molly. He thought that, like his parents, she was gone. Until one of Moriarty's quips alerted him of the truth.

"Oh, don't tell me you've figured out where she is. She's comfortable there, best room in the place."

Moriarty's cruel cackling followed Sherlock down the stairs.

She was in his room, chained, in the strait jacket, dirty, ragged, and terrified. She was cut and beaten and bruised, and as he entered, she cowered away from him and began to whimper softly.

A voice, gravelly and gruff, resounded above him.

_Doesn't she looked beautiful?_

Sherlock had no response.

Until that day, he would have told anyone who believed in heaven and hell and demons and gods that they were poor, gullible, excuses. Churches were wastes of space and priests were money grubbing, hypocritical men using their gullibility to line their pockets.

Now, he prayed to a God he wasn't certain he believed in that something would change, before the captivity and cruelty of his own mind destroyed him.

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Whoopsie XD

Thanks so much for the reviews, **MorbidByDefault, Rose of Zakarisz, Aquitaine85 , chibisiam, Zora Arian, GirlatTheRockShow182, Brytte Mystere,** and **Anna 'God Of Something.**

And thanks to Liathwen for being a speedy beta XD

Until Next Time!


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